Synthesis,spectroscopic characterization,thermal stability and biological studies of mixed ligand complexes of gemifloxacin drug and 2,2′-bipyridine with some transition metals

Research on Chemical Intermediates - The mixed ligand Zn(II), Zr(IV), Pd(II), Ce(IV), Th(IV), and U(VI) complexes of gemifloxacin and N-donor 2,2′-bipyridine have been prepared. These...     

p-Tolylimido rhenium(V) complexes – Synthesis,X-ray studies,spectroscopic characterization and DFT calculations

The p-tolylimido rhenium(V) complexes [Re(p-NC₆H₄CH₃)X₃(EPh₃)₂] (X = Cl, Br; E = As, P) and [Re(p-NC₆H₄CH₃)Cl₂(hmpbta)(PPh₃)]·MeCN have been synthesized and characterized spectroscopically and structurally. The electronic spectra of [Re(p-NC₆H₄CH₃)Cl₃(PPh₃)₂] and [Re(p-NC₆H₄CH₃)Cl₂(hmpbta)(PPh₃)](Hhmpbta-2-(2′-hydroxy-5′-methylphenyl)benzotriazole) were investigated at the TDDFT level employing B3LYP functional in combination with LANL2DZ. Additional information about bonding between the rhenium atom and p-tolylimido ligand in the complexes [Re(p-NC₆H₄CH₃)Cl₃(PPh₃)₂] and [Re(p-NC₆H₄CH₃)Cl₂(hmpbta)(PPh₃)] was obtained by NBO analysis.     

Synthesis and spectroscopic characterization of new heteroleptic ruthenium(II) complexes incorporating 2-(2′-pyridyl)quinoxaline and 4-carboxy-2-(2′-pyridyl)quinoline

Starting from cis-[Ru(dcbpyH₂)₂Cl₂] (1), two new heteroleptic ruthenium(II) complexes, [Ru(dcbpyH₂)₂(L¹)](NO₃)₂ (L^1?=?2-(2′-pyridyl)quinoxaline (2), and [Ru(dcbpyH₂)₂(L²)](NO₃)₂ (L^2?=?4-carboxy-2-(2′-pyridyl)quinoline (4); dcbpyH_2?=?2,2′-bipyridine-4,4′-dicarboxylic acid), were synthesized and spectroscopically characterized. During the preparation of 2 and 4, the homoleptic [Ru(dcbpyH₂)₃]Cl₂ complex (3) was isolated as a side product. Characterization includes IR and Raman spectroscopy, UV-Vis, multinuclear NMR spectroscopy, elemental, and ESI-mass spectrometric analyses.     

Synthesis,spectroscopic, thermal,and biological activities of mixed ligand complexes containing E-N′-(3,4,5-trimethoxybenzylidene)benzofuran-2-carbohydrazide and 2-aminothiophenol

Complexes [M(L)(L′)Cl?·?H₂O], where M?=?Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and Hg(II), L?=?ligand derived from reaction between benzofuran-2-carbohydrazide and 3,4,5-trimethoxybenzaldehyde (TMeOBFC) and L′?=?2-aminothiophenol (2-atp), have been synthesized. The structures of the complexes have been proposed from analytical data, IR, UV-Vis, ¹H NMR, direct analysis in real time-mass spectra, ESR spectral data, magnetic, and thermal studies. The complexes are soluble in DMF and DMSO. Molar conductance values indicate that the complexes are non-electrolytes. Antibacterial and antifungal activities of the ligands and their metal complexes have been obtained against bacteria Escherichia coli and Staphylococcus aureus and against fungi Aspergillus niger and Aspergillus flavus.     

ZnII and HgII complexes of 2,2′-diamino-4,4′-bis(1,3-thiazole) (DABTZ), spectroscopic,thermal and structural studies

New zinc(II) and mercury(II) complexes of 2,2′-diamino-4,4′-bis(1,3-thiazole) (DABTZ), [M(DABTZ)(CH₃COO)₂], have been synthesized and characterized by elemental analysis, IR-, ¹H NMR-, ¹³C NMR spectroscopy and studied by thermal analysis and X-ray crystallography. The structural characterization of the [Zn(DABTZ)(CH₃COO)₂] complex shows the complex to be a monomer and the Zn coordinated by two nitrogen atoms of the “DABTZ” ligand and four oxygen atoms of the acetate anions.     

Synthesis,characterization and antimicrobial activity studies of N - N ′-tetracarboxydiethyloxamide ligand and its metal(II) complexes

N-N′-tetracarboxydiethyloxamide (hereafter abbreviated as H₆L) was prepared by using L-aspartic acid and diethyl oxalate (DEO). A series of binuclear complexes of divalent metal chlorides viz. Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) with H₆L have been prepared. Spectral studies (IR, UV and NMR) magnetic susceptibility, elemental analysis and molar conductance measurements confirm the formation of binuclear complexes, [M₂H₂L]/[M₂H₂L?·?4H₂O]. Electronic absorption spectra and magnetic susceptibilities suggest square-planar stereochemistry for Cu(II) and tetrahedral for Zn(II) complexes. Mn(II), Co(II), and Ni(II) coordinate two molecules of water and consequently show octahedral geometry. The in vitro antimicrobial activity of the synthesized compounds is discussed against bacterial strains such as S. aureus, S. epididermis, K. pneumonia, S. typhi, P. aerugenosa, and B. subtilis A. brasilense. The metal complexes show higher activity against all the microorganisms than the ligand.     

Ruthenium(II) complexes of 2-(2′-pyridyl)naphthoimidazole: synthesis,characterization and DNA-binding studies

The perchlorate salts of two new ruthenium(II) complexes incorporating 2-(2′-pyridyl)naphthoimidazole are synthesized in good yield. Complexes [Ru(phen)₂(PYNI)]²⁺ (phen = 1,10-phenanthroline) 1 and [Ru(dmp)₂(PYNI)]²⁺ (dmp = 2,9-dimethyl-1,10-phenanthroline, PYNI = 2-(2′-pyridyl)naphthoimidazole) 2 are fully characterized by elemental analysis, FAB-MS, ES-MS, ¹H NMR and cyclic voltammetric methods. The DNA-binding behavior of the complexes have been studied by spectroscopic titration, viscosity measurements and thermal denaturation. Absorption titration and thermal denaturation studies reveal that these complexes are moderately strong binders of calf-thymus DNA (CT-DNA), with their binding constants spanning the range (2.73–5.35) × 10⁴ M^?1. The experimental results show that 1 interacts with calf thymus DNA (CT-DNA) by intercalative mode, while 2 binds to CT-DNA by partial intercalation.     

Synthesis,spectroscopic, antimicrobial and anti-inflammatory studies of 5(2′-hydroxyphenyl)-3-(4-x-phenyl)pyrazolinates of copper(II) and their addition complexes with donor ligands

Complexes of copper(II) with 5(2′-hydroxyphenyl)-3-(4-x-phenyl)pyrazolines, (C₁₅H₁₂N₂OX)₂Cu [X =–H,–Cl,–CH₃,–OCH₃] have been synthesized with their addition complexes with 2,2′-bipyridine, 1,10-phenanthroline and triphenylphosphine. The complexes were characterized by elemental analyses, molecular weight measurement, magnetic, conductivity measurement, IR, electronic, ³¹P NMR, ESR and FAB mass spectra. The complexes were examined for crystalline/amorphous nature through XRD. Square-planar geometry around copper(II) is suggested with two bidentate pyrazoline ligands. In the additional complexes pyrazoline is monodentate. The bidentate and monodentate behavior of pyrazoline ligands was confirmed by IR and ³¹P NMR spectral data. All complexes were tested for in vitro antibacterial and antifungal activity and exhibit very good antibacterial and antifungal activity; coordination has a pronounced effect on the microbial activities. The brine shrimp bioassay was also carried out to study their in vitro cytotoxic properties. All complexes and adducts displayed potent cytotoxic activity against Artemia salina. Anti-inflammatory activity was also carried out by the carrageenan induced rat paw edema test. The complexes and adducts were found to have higher anti-inflammatory activity.     

Synthesis,Mössbauer,and IP spectroscopic studies and thermal behavior of diorganotin(IV) complexes with carbohydrate ligands

A series of diethyltin(IV) complexes with carbohydrate ligands (aldoses, polyalcohols, sugar acids, sugar amines, and di- and trisaccharides] was prepared. The compositions of the complexes were determined by standard analytical methods. The results showed that complexes formed containing the diethyltin moiety and the carbohydrate ligand in 11 ratio. The IR spectra were consistent with the presence of tin—carbohydrate oxygen vibrations in the compounds. The comparison of experimental quadrupole splitting values with those calculated on the basis of the partial quadrupole splitting (PQS) concept revealed the compounds to be of three types: complexes in with the central tin(IV) atoms are present in purely trigonal bipyramidal surroundings, ones with the tin(IV) atoms present in purely octahedral surroundings, or ones with both octahedral and trigonal bipyramidal arrangements in approximately 11 ratio. The thermal decompositions showed that some of the complexes decompose via the reduction of tin(IV) to SnO as the final tin-containing product, some of them decompose without reduction, to give SnO₂, and some decompose to give indefinite final tin-containing products.     

Synthesis,spectroscopic, antibacterial and antifungal studies of nickel(II)5(2′-hydroxyphenyl)-3-(4-X-phenyl)pyrazolinates and their addition complexes with N and P donor ligands

A number of complexes of nickel(II) with 5(2′-hydroxyphenyl)-3-(4-X-phenyl)pyrazolines of the type (C₁₅H₁₂N₂O ··· X)₂Ni [where X = H, Cl, CH₃ and OCH₃] were synthesized by the reaction of anhydrous nickel(II) chloride with sodium salts of pyrazoline in 1 : 2 molar ratio. Their addition complexes with 2,2′-bipyridine, 1,10-phenanthroline and triphenylphosphine were prepared in 1 : 1 molar ratio. These complexes were characterized by elemental analyses, molecular weight, magnetic, conductivity, IR, electronic, ¹H, ¹³C, ³¹P NMR and FAB mass spectral data. All complexes are amorphous. Square planar geometry around nickel confirms the presence of two bidentate pyrazoline ligands in nickel(II)5(2′-hydroxyphenyl)-3-(4-X-phenyl)pyrazolinates. In the addition complexes pyrazoline is monodentate. Bidentate and monodentate pyrazoline was confirmed by IR, ¹H, ¹³C and ³¹P NMR spectral data. All the metal complexes exhibit very good antibacterial and antifungal activity. Coordination of metal ion has pronounced effect on the microbial activities of the ligand. The brine shrimp bioassay was also carried out to study their in vitro cytotoxic properties; all complexes and adducts display potent cytotoxic activity against Artemia salina.     

Synthesis, characterization and cyclic voltammetric studies of β-ketooximato ruthenium(II) complexes

Summary -Ketooxime [RC(O)C(NOH)R] (R = Me or Ph) ligands (HL) react with [Ru(PPh₃)₃Cl₂] in refluxing EtOH to yield [Ru(PPh₃)₂(L)₂] complexes. For R = Me, one isomer was obtained, while two isomers were isolated when R = Ph, due to a bulk effect. The complexes are diamagnetic and absorb intensely in the vis. region due to MLCT transitions. In MeCN and CH₂Cl₂ solution, Ru^II-Ru^III oxidation occurs in the 0.69–0.92 V versus s.c.e. range. The oxidation potential depends on both the electronic nature of R and the stereochemistry of the complexes.     

Synthesis,characterization, and biological activity studies on (E)-N′-[2-hydroxy-1,2-di(pyridin-2-yl)ethylidine]aroyl hydrazides and their copper(II) complexes

The reaction of copper(II) salts with (E)-N-(2-hydroxy-1,2-di(pyridin-2-yl)ethylidene)aroyl hydrazide (H₂L¹, H₂L², H₃L³) or (E)-N-(2-hydroxy-1,2-di(pyridin-2-yl)ethylidene) isonicotinohydrazide (H₂L⁴) afforded the complexes [(L)Cu(H₂O)₃], [(H₂L)Cu(OAc)(H₂O)], [(HL)Cu(OAc)] _n , [(H₂L)Cu(H₂O)](ClO₄)₂ and [(H₂L)Cu(OAc)(H₂O)], where n = 1 or 2 and L is the dinegative ion of the ligands. The ligands and their complexes are characterized by elemental analyses, spectral (IR, NMR, electronic, and ESR) and magnetic studies. The FT-IR indicates that the ligands are neutral or anionic polydentate. The number of the coordinating centers depends on the nature of the metal used and the reaction conditions. The room temperature magnetic moment values, electronic spectra and ESR data indicate square planar, trigonal bipyramidal, square pyramidal, and distorted octahedral ligand fields around copper(II). Thermal decomposition of the complexes was monitored by TG and DTG under N₂ and the thermal decomposition mechanisms are given. The compounds were screened for their antimicrobial activities on some Gram-positive and Gram-negative bacterial species. The free ligands are inactive against all studied bacteria. The complexes have variable activity with the most active [(H₂L)Cu(H₂O)](ClO₄)₂, where H₂L is H₂L¹ or H₂L². The minimum inhibition concentrations for these two complexes were determined. These biological activity results are related to the structures of the compounds.     

Manganese(II) complexes of 5-(4-pyridyl), 5-phenyl and 5-(4-methoxy-phenyl)-1,3,4-oxadiazole-2-thione containing 2, 2′-bipyridyl/ethylenediamine: synthesis,spectral, and X-ray characterization

Three new mixed ligand complexes [Mn(4-pytone)₂(bipy)₂]bipy (1), [Mn(pot)₂(en)₂] (2) and [Mn(4-mot)₂(en)₂] (3) (4-pytone = 5-(4-pyridyl)-1,3,4-oxadiazole-2-thione, pot = 5-phenyl-1,3,4-oxadiazole-2-thione, 4-mot = 5-(4-methoxy-phenyl)-1,3,4-oxadiazole-2-thione) have been prepared containing bipy/en as coligands. The starting material potassium N-(aryl-carbonyl)-hydrazinecarbodithioates (RCONHNHCSSK) underwent cyclization during complexation in the presence of bipy or en to give the corresponding 5-aryl-1,3,4-oxadiazole-2-thiones. The complexes have been characterized by physicochemical techniques and single crystal X-ray structure determination. In all cases, the manganese has a six coordinate octahedral arrangement coordinated by 4N atoms of two bipy/en and two covalently bonded N atoms of the oxadiazole-2-thione anions.     

Synthesis, spectroscopic, powder X-ray diffraction and DNA binding studies on copper(II) complexes of 4,4′-diaminodiphenyl sulfone

Four new Cu(II) complexes of 4,4??-diaminodiphenyl sulfone (DDS) with different anions (chloride, sulfate, nitrate or acetate) were synthesized and characterized by elemental analysis, electronic absorption, IR, magnetic moment, thermal analysis and powder X-ray diffraction studies. It was found that the pure DDS and complex [Cu₂(DDS)₂(NO₃)₂].(NO₃)₂ (3) crystallize in orthorhombic system while the complexes [Cu₂(DDS)₂].Cl₄ (1), [Cu₂(DDS)₂].(SO₄)₂ (2), and [Cu₂(DDS)₂].(CH₃COO)₄ (4) crystallize in monoclinic system. The crystallite sizes of complexes have smaller values as compared to pure DDS. Infrared studies suggest that the coordination of NH₂ of DDS with Cu(II) ion. The binding of the complexes with calf thymus (CT) DNA was investigated by electronic absorption titration, fluorescence measurements and DNA thermal denaturation. The spectroscopic studies together with the DNA melting studies indicated that the complexes may bind to CT-DNA in a non-intercalative mode.     

Synthesis,characterization, and biological evaluation of silver(I) complexes of N′-(1-(pyrazin-2-yl)ethylidene)picolinohydrazide

Three Ag⁺ complexes, [Ag(L)(NO₃)]_n (1), {[Ag(L)]·SbF₆·CH₂Cl₂}_n (2), and {[Ag(L)]·SO₃CF₃·CHCl₃}_n (3), based on a hydrazone ligand L have been obtained (L = N′-(1-(pyrazin-2-yl)ethylidene)picolinohydrazide) and characterized. Complexes 1–3 all show 1-D chain-like structures. Their antibacterial activity and interaction with serum albumin were investigated. These results indicate that these complexes show good antibacterial activities and binding affinity to serum albumin.     

Synthesis, spectroscopic studies of new water-soluble Co(II) and Cu(II) macrocyclic complexes of 4,15-bis(2-hydroxyethyl)-2,4,6,13,15,17-hexaazatricyclodocosane: their interaction studies with calf thymus DNA and guanosine 5′ monophosphate

New water soluble Co(II) 1, Ni(II) 2 and Cu(II) 3 complexes of 4,15-bis(2-hydroxyethyl)-2,4,6,13,15,17-hexaazatricyclodocosane Co(II) were synthesized and characterized by various techniques, viz. elemental analysis, conductivity measurements, infrared, electronic, ESI-MS, ¹H and ¹³C NMR spectroscopy. Molar conductance measurements in aqueous solution showed that complexes 1, 2 and 3 are ionic in nature. On the basis of spectroscopic data, a square planar geometry was assigned to the complexes involving four N-atoms of the two cyclohexane moieties. Interaction studies of 1 and 3 with CT-DNA were carried using UV/Visible absorption spectroscopy, fluorescence spectrophotometry, cyclic voltammetry and viscosity measurements. Absorption spectral traces reveal 27.7 and 23.3% hyperchromism for complexes 1 and 3, respectively indicative of strong binding to CT-DNA. These results were authenticated by fluorescence quenching experiments and viscosity measurements. The intrinsic binding constants K _b of 1 and 3 are 2.94 × 10⁴ and 2.71 × 10⁴ M^?1, respectively. Early transition metals show preference for O6 position while later ones copper and cobalt prefer N7 position of DNA base guanine. To validate this hypothesis, interaction studies of copper (II) and cobalt (II) complexes were carried out with 5′GMP, which revealed electrostatic interactions are more favored along with hydrogen bonding than coordinate covalent interaction to N7 position of guanine.     

Synthesis,characterization, in vitro,and in silico studies of 4-(2′-hydroxybenzoyl) and 4-(2′-hydroxynaphthoyl)-thiabenzene-1-methyl-1-oxides

A variety of 4-(2′-hydroxybenzoyl) and 4-(2′-hydroxynaphthoyl) thiabenzene-1-methyl-1-oxides have been prepared by the reaction of dimethylsulfoxoniummethylide with 3-formyl-chromones and screened for their anticancer activities on lung cancer cell line by in vitro and in silico studies.     

Synthesis,spectroscopy and X-ray studies of [N′-(2-hydroxy-3-methoxybenzylidene)-4-methylbenzenesulfonohydrazide]uranyl(IV)

The C₃₀H₃₀N₄O₁₀S₂U complex (I) has been investigated and characterized by single crystal X-ray diffraction (CIF file CCDC no. 970349), IR and UV-Vis spectroscopic techniques. X-ray results show that the title compound crystallizes in the monoclinic system, space group P2₁/c with a = 14.8219(14), b = 11.6177(11), c = 20.0854(15) Å, β = 104.268(9)°, V = 3351.9(5) ų and Z = 4. In the title structure, the U atom has a distorted pentagonal-bipyramidal geometry with a tetradentate Schiff base ligand in the equatorial plane and oxo atoms in the axial positions. The C-S-N(H)-N linkage is non-planar, the torsion angle being ?98.7(15)° and the S atom showing a tetrahedral environment. The crystal packing occurs intra-inter molecular N-H?O and C-H?O hydrogen bonds.     

Synthesis and X-ray structural characterization of dioxomolybdenum(VI) complexes with N′-(5-chloro-2-hydroxybenzylidene)-4-methylbenzohydrazide and N′-(2-hydroxybenzylidene)-4-methylbenzohydrazide

Two new dioxomolybdenum(VI) complexes, [MoO₂(ClHm)(CH₃OH)] (I) and [MoO₂(Hm)(CH₃OH)] (II) with the hydrazone ligands H₂ClHm and H₂Hm derived from 4-methylbenzohy-drazide with 5-chlorosalicylaldehyde and salicylaldehyde, respectively, have been synthesized and structurally characterized by physicochemical methods and single-crystal X-ray determination. The crystal of I crystallizes in the triclinic space group \(P\bar 1\), with a = 7.839(2), b = 9.656(3), c = 11.548(4) Å α = 88.885(3)°, β = 87.454(3)°, γ = 88.996(3)°, V = 873.0(5) ų, Z = 2, R ₁ = 0.0292, wR ₂ = 0.0685, S = 1.092. The crystal of II crystallizes in the triclinic space group \(P\bar 1\), with a = 7.780(2), b = 10.584(3), c = 10.628(3) Å, α = 91.462(3)°, β = 104.818(3)°, γ = 103.288(3)°, V = 820.1(4) ų, Z = 2, R ₁ = 0.0403, wR ₂ = 0.0784, S = 1.065. An X-ray analysis indicates that the structures of both complexes are similar to each other. The molybdenum atom in each complex is in an octahedral coordination environment constructed by two oxo groups, an NO₂ donor set of the hydrazone ligand, and one methanol O atom.